Question 150363
let see:
+3x+12y|-12
-6x-17y|+03

Coefficient matrix
+3+12|-12
-6-17|+03

+1+4|-4    -----|> 1/3R1
*0+7|-21   -----|> 6R1+R2

+1+4|-4     
*0+1|-3    -----|> 1/7R2

REDUCED TO:
+1*0|+8    -----|> -4R2+R1
*0+1|-3    

SOLUTION:
3(8)+12(-3)=-12
-6(8)-17(-3)=3
X= 8, Y=-3